When driving on I-44 from Tulsa to OKC you pass a sign that says “Entering Oklahoma City” then it’s 13 miles of nothing before you hit I-35. They did the same annexation along I-40 east of the city. Tinker AFB is the southeast corner of what most would consider OKC, but city limits go another 12 miles east of Tinker along I-40 that’s sparsely populated.
I have no idea why all of that is OKC. Along I-44 east of town there is probably 20 square miles of land that’s in the city limits & probably has less than 5,000 people living there.